Max schafer



M. SCHAFER AND A. KRAUS. SHORT CIRCUITING DEVICE FOR ELECTRICAL mmnou APPARATUS.

APPLICATION FILED AUG-26.1919- Patented Dec. 27, 1921.

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UNITED STATES PATENT OFFICE.

MAX SCHAFER, OF STUTTGABT, AND ADOLF KRAUS, 0F CANNSTATT, GERMANY,

ASSIGNORS TO FIRM OF ROBERT BOSCH AKTIENGESELLSCHAFT, 0F STUTT- GART, GERMANY.

SHORT-CIRCUITING DEVICE FOR ELECTRICAL IGNITION APPARATUS.

Specification of Letters'Patent.

Patented Dec. 27, 1921.

Application filed August 26, 1919. Serial No. 328,660.

To all whom it may concern:

Be it known that we, MAX SGHAFER, engineer, a citizen of Germany, residing at and whose post-office address is Stuttgart, Johannesstrasse 96, Germany, and Anoni Knauaforeman, a citizen of Germany, residing at and whose post-office' address is; Cannstatt, Bryestrasse 8, Germany, have invented certain new and useful Improvements (for which we have filed applications in Germany, October 7, 1915; Germany, Aug 80, 1918; Austria, March 27, 1916; Switzerland, May 26, 1919, and Sweden, May 80, 1919,) in Short-Circuiting Devices for Electrical Ignition Apparatus; and we do hereby declare the following to be a full,

clear, and exact description of the inven This invention relates to a short-circuit ing device for electric ignition or sparking apparatus which short-circuits the ignition current by means of a fly-weight swung outward by centrifugal forceon a certain adjustable speed of-revolution being reached.

In the drawing a manner of carrying out the invention in connection with an interrupter is shown, Figure 1 representing an end-view and Fig. 2 a longitudinal section. Fig; 3 illustrates a short-circuiting speed governor that is geared to the ignition current magnetoby spur-wheels The cup-shaped casing a, which is furnished with a hub, and the interrupter are fastened by the interrupter'screw b to the ignition apparatus in the well known manner. A. hole is drilled at right angles to the axis of rotation through the casing a and this hole acts as a guide for a rod to which a fly-weight c is attached. The upper part of the rod has a thread onto which a known form of serrated coupling-nut e is screwed, the loose part of the latter being pressed against the threaded portion by a spiral spring 7", the fly-weight being thus alsopulled up against the casing when it is at rest. A bush 9 screwed into the casing a serves as a guide for the rod d and as a casing for the spiral spring 7''. The middle portion of the rod is shaped in the form of a ring h so as to enable the rod topass around the fastening screw 6. The lower part/i of the rod, to which the fly-weight c is attached, is inserted in a guiding slot cut nto the casing a and the part 2' is inclosed in this slot by an elastic or spring is that fits into a circular groove. This ring being easy to remove, the rod can easily be taken out of the casing, and besides it reduces the friction between the guide portions and the rod to a minimum. Attached to the fly weight 0 is a leaf-spring Z, which in turn carries a platinum contact m, while the other platinum contact n is arranged on a support 0 screwed fast to, but insulated from, the casing a.

The electrical connection between the casing a and the fly-weight c is established by a strip 7) consisting of annealed copper sheet. A means for conducting the current from the casing a to the movable fly-weight c is thus obtained by which no additional tension is caused that would be likely to affect the adjustment of the fly-weight for a desired speed of revolution.

. The current is conducted from the interrupter to the short-circuiting device through a slit thimble or sleeve 1* mounted upon the interrupter disk 9 and through a pin 8 that is arranged on the contact support 0 and fits into the said sleeve.

The manner in which short-circuiting device operates will be apparent from the drawing.

On the speed of revolution for which the tension of the spiral spring is adjusted being reached or exceeded the contact m, a will close and thus short-circuit the current from the interrupter so-that ignitions in the engine will be suppressed and the speedof the engine lowered. As soon as it has sunk to a point where the tension of the spring f exceeds the centrifugal force the contact at m, n is opened and the regular ignitions recommence.

It has been found that in engines in which violent vibration occurs the fluctuations of the speeds at which the short-circuiting gov- 'ernor suppresses the ignitions are extremely large and that during the ignition-suppressing-operation irregular ignitions due to vibrations continue to occur, 2'. c. the short-circuiting governor opens the short-circuit and the speed of revolution of the engine rises considerably more than is desired after short-circuiting of the ignition current has taken place. In the device shown in Fig.

' 3 thi's drawback is removed by driving the short-circuiting governor at a higher speed than-the ignition apparatus or'rnagneto 'with' the aid of a suitable speed-raisingmeans such as spur wheels. By this means the centrifugal force of the fly-weight of the short-circultin overnor is considerabl 1n- 6 b creased sothat when a certain speed is reached the fly-weight securely closes and I ing of ignitions.

The short-circuiting governor employed in the design shown, by way of example,- in Fig. 3, may' beof the type illustrated in Figs. 1 and 2 or of any other type. It is not fixed direct to the armature-as in the case of Figs. 1 and 2, but is driven by'the armatureshaft .t by gear wheels e, 2 so as to revolve at a much higher speed than the said shaft; Hence, after the fiy-weight has once reached the much higherspeed of revolution-at which the short-circuitingcontact m, a is designed to be closed, its centrifugal force will besuch as to keep the contact much more securely closed than in the above design when vibrations of th ignition apparatus occur, sothat the irregular ignitions and the appreciable fluctuations of the speedof revolution of the engine, which are apt to occur when" ignitions are suppressed, are" prevented. The spring u'conducts the ignition current from the armature to the interrupter.

Practical tests carried, out with this device have shown that in the case of a benzin engine, for example, with a speed of revolution of about 1800 per. minute the fluctuations due tosuppression ofthe ignitions by the short-circuiting governor only amountedto about 20 to 25 revolutions per minute, while the fiunctuations of the sajmeengine, equipped with a short-circuiting governor mounted on the armature shaft or connected to the armature of the ignition .inagneto, amounted to about 200 per minute when ignitions were suppressed by the governor.

. We claim l. 'A short-circuiting device for electrical ignition apparatus comprising, a casing, a

rotary interrupter disk adapted to be;

screwed to the said casing, a fiy-weighua mechanical spring connection between the fl -wei ht and the easin a contact carried by the saidfly-weight, a second contact opposite to thesaid fly-weight contact,'a support fixed to the casing and supporting the second contact, a thimble mounted on the 2. A short-circuiting device for electrical rim of the cap-shaped casing, the said screw passing'through the ring-shaped bond, the upperrod extending through the radial tube, while the lower rod is guided in a radial slot in the said rim that is opposite to the said tube, an adjustable spring abutment on the said upper rod, a pressure spring abutting a its one end against the Said abut ment and holding the fly-weight guide'with its fly-weight in a normal position, a contact carried by the said fly-weight, a second con tact opposite to the said fly-weight contact,

a support fixed to the casing and supporting the second contact, a thimble mounted on the interrupter disk, and a current-conducting-pin attached'to the said inserted in the said thimble.

3. A shortwircuiting device for electrical ignition apparatus comprising, a cap-shaped casing, a rotary interrupter disk, a screw located in the centerof the disk and holding the casing and the disk together, a fly-q weight guide consisting of anupper rod, a lower rod and a ring-shaped bond ]011l1I1g the upper and lower rods, a fly-weight attached to the lower rod, a radial :tube- .0 7 support and screwed into a'radial threaded hole in the rim of the cap-shaped casing, the said screw passing through the ring-shaped bond, the 1 upper rod extending through the radial tube,

while the lower rod is guided in a radial slotin the said rim that is opposite to the said tube, an adjustable spring 'abutment' on thesaid upper rod, a pressure spring' abutting at its one'end against the said abutnient'and holding the fly-weight guide with its fly weight in a normal position, a contact carried by the said fly-weight, a second contact opposite to the said fly-weight contact, a support fixed to the casing and supporting theseeond contact, a thimble-mounted. on the interrupter eis k, a current-conducting-pin attached to the said support and inserted in the saidthimble, and a flexible ring adhering by itscontractlon to the rim' or the cap-shaped casing and constltuting a border at the open end of the said slot that is cut into the said rim, thus forming" a closed guide hole for thesaid lower rod.

&. A short circuiting'device for electrical ignition apparatus comprising, a casing, a

rotary interrupter disk adapted to be screwed to the said casing, a fly-weight, a mechanical spring connection between the fly-weight andthe casing, a leaf-spring on the said fly-weight, a fly-Weight contact carried by the leaf-spring, a second contact opposite to the said fly-Weight contact, a support fixed to the casing and a support therefor fixed to the casing and insulated therefrom, a thimble' mounted on the interrupter disk, a current-conducting-pin attached to the said support and inserted in the said thimble, and an electrical connection between the fly-Weight contact and the said casing, the electrical connection consisting of a ribbon made of annealed copper sheet. v

5. A short circuiting device for electrical ignition apparatus comprising a casing, a rotary interrupter disk adapted to be screwed to the said casing, a shaft carrying the said interrupter disk and said casing and connected by gearings to the shaft of the ignition apparatus, said gearings being of such transmission ratio that the interrupter shaft operates at a speed higher than that of the ignition apparatus, a fly weight, a mechanical spring connection between the fly Weight and the casing, a contact carried by the said fly-Weight, a second contact, a support fixed to the casing and supporting the second contact, a thimble mounted on the interrupter disk and a current conducting pin attached to the said support and inserted in said thimble.

In testimony whereof We aifix our signatures, in presence of two Witnesses.

MAX SCHKFER. ADOLF KRAUS. Witnesses:

ADOLF SIBBERS, HERMANN SCHNEIDER. 

